carb jetting

[Rota Ash]

hey lads i have an 02 RM250, its basically in stock form besides an fmf gnarly pipe and a cut down silencer, it's in the process of getting a new ring in it at the moment as the compression was down to 160, the top end is in now getting a bit of a touch up port wise.

here is the plug after doing a fair bit of beach riding (trying to keep up with 450's )



the jetting is bascially stock : #168 main, air screw out 1.5 turns, and needle clip in 4th position with a #52 slow jet, should i just drop the needle position say to the 3rd position, drop the main jet to a #165 or back the air screw out 1/2 a turn i run full synthetic motorex oil at 40:1 and 98ron pulp.

by the way the 4 stokes were beating me and there heavier riders.

[admiral]

hey lads i have an 02 RM250, its basically in stock form besides an fmf gnarly pipe and a cut down silencer, it's in the process of getting a new ring in it at the moment as the compression was down to 160, the top end is in now getting a bit of a touch up port wise.

here is the plug after doing a fair bit of beach riding (trying to keep up with 450's )



the jetting is bascially stock : #168 main, air screw out 1.5 turns, and needle clip in 4th position with a #52 slow jet, should i just drop the needle position say to the 3rd position, drop the main jet to a #165 or back the air screw out 1/2 a turn i run full synthetic motorex oil at 40:1 and 98ron pulp.

by the way the 4 stokes were beating me and there heavier riders.

before swapping the brass i would first try raising the clip to the second from the top clip position as it is rich. i don't know you local temp. and humidity conditions or your jetting experience. you will feel the difference right away. the reason i say two clip positions is it is easier to feel the change if you have never done it before. see how the bike responds by just warming it up in place. if it seems responsive then ride it around twisting the throttle to feel how it pulls. i wouldn't go do deep sand runs right away.

[Chokey]

'99-'03 RM 250s respond well to the next leaner slide.

Suzuki changed to the leaner slide from the factory in '04.

[eprovenzano]

Before doing any jetting changes, freshen up the top end.  Engines low on compression can mask jetting issues.  Always start with a freshened engine when making jetting changes.

[Rota Ash]

yeh just freshened the motor up, got a port job on it and backed off the air screw 1/4 of a turn and put a new plug in, still gotta check the plug, i'd say its still rich as but i gotta pull the carb apart as the needle and seat does not seem to be sealing, if the bikes off it leaks fuel.

[eprovenzano]

yeh just freshened the motor up, got a port job on it and backed off the air screw 1/4 of a turn and put a new plug in, still gotta check the plug, i'd say its still rich as but i gotta pull the carb apart as the needle and seat does not seem to be sealing, if the bikes off it leaks fuel.

I'd repair the carb before makeing any jetting changes.  I own a KTM which is real sensitive to jetting changes.  I've found from experience that you need to make sure the top and bottom ends are tight. Make sure your carb is not leaking and the float is set to the proper height.

After all the above, then start changes for your jetting.